1. Field of the Invention
The present invention relates to measurement of horizontal incline, and more particularly to an inclinometer that generates a measurement signal based on position equilibration of a magnetic element.
2. Description of the Related Art
Incline-measurement instruments find application in a wide variety of industrial and research environments. For example, geotechnical engineers utilizes these devices to track the underground boring tools employed in oil prospecting, well construction, and the installation of subterranean pipes and cables, while numerous types of aerospace, automotive, and robotic equipment incorporate inclinometers as standard components.
Because traditional mechanical inclinometers must take into account the effects of friction, which would otherwise distort measurement signals generated by elements responsive to the force of gravity, more modern designs frequently utilize mobile elements fully bathed in a liquid. Magnetic elements, for example, are often suspended in ferrofluids--i.e., colloids that contain suspended magnetic particles and which respond to an applied magnetic field as if the fluid itself possessed homogeneous magnetic characteristics. Various measurement arrangements have been employed to detect movement of a magnet floating within a ferrofluid sheath or to measure the force exerted on such an element by gravity, and to derive therefrom a signal indicative of the degree of tilt.
Unfortunately, the requirement of immersing a measurement element in a liquid imposes design limitations. First, such an inclinometer device must remain fully sealed to prevent escape of the liquid. Second, response times necessarily depend on the viscosity of the liquid within which the element moves, a factor that can prove critical in high-performance applications. And depending on the volumes involved, to be fully submerged a mobile magnetic element can require a considerable amount of ferrofluid, adding cost to the device.